A great tract of the volcanic region appears to have remained almost undisturbed to the present day, affected by sub-aerial erosion alone.

The geological horizon of the Deccan trap cannot be precisely defined, but is now vaguely stated as 'the close of the cretaceous period'.

The 'steps', or conspicuous terraces, traceable on the hill-sides for great distances, are explained as being 'due to the outcrop of the harder basaltic strata, or of those beds which resist best the disintegrating influences of exposure'.
The general horizontality of the Deccan trap over an area of not less than 200,000 square miles, and the absence of volcanic hills of the usual conical form, are difficulties which have caused much discussion.

Some of the 'old volcanic vents' appear to have existed near Poona and Mahableshwar.

The entire area has been subjected to sub-aerial denudation on a gigantic scale, which explains the occurrence of the basalt as the caps of isolated hills.